Sender: Paolo Bonzini <paolo.bonzini@gmail.com>
Message-ID: <3bf8d500-0c1e-92dd-20c8-c3c231d2cbed@redhat.com>
Date:   Thu, 9 Dec 2021 15:29:04 +0100
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Subject: Re: [PATCH v3 00/26] KVM: x86: Halt and APICv overhaul
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To:     Sean Christopherson <seanjc@google.com>,
        Maxim Levitsky <mlevitsk@redhat.com>
Cc:     Joerg Roedel <joro@8bytes.org>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
        kvm@vger.kernel.org, iommu@lists.linux-foundation.org,
        linux-kernel@vger.kernel.org
References: <20211208015236.1616697-1-seanjc@google.com>
 <39c885fc6455dd0aa2f8643e725422851430f9ec.camel@redhat.com>
 <8c6c38f3cc201e42629c3b8e5cf8cdb251c9ea8d.camel@redhat.com>
 <YbFHsYJ5ua3J286o@google.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
In-Reply-To: <YbFHsYJ5ua3J286o@google.com>
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On 12/9/21 01:02, Sean Christopherson wrote:
> RDX, a.k.a. ir_data is NULL.  This check in svm_ir_list_add()
> 
> 	if (pi->ir_data && (pi->prev_ga_tag != 0)) {
> 
> implies pi->ir_data can be NULL, but neither avic_update_iommu_vcpu_affinity()
> nor amd_iommu_update_ga() check ir->data for NULL.
> 
> amd_ir_set_vcpu_affinity() returns "success" without clearing pi.is_guest_mode
> 
> 	/* Note:
> 	 * This device has never been set up for guest mode.
> 	 * we should not modify the IRTE
> 	 */
> 	if (!dev_data || !dev_data->use_vapic)
> 		return 0;
> 
> so it's plausible svm_ir_list_add() could add to the list with a NULL pi->ir_data.
> 
> But none of the relevant code has seen any meaningful changes since 5.15, so odds
> are good I broke something :-/
> 

Ok, I'll take this.

Paolo